Shock absorber



Aug. 22, 1950 E. F. Ros'sMAN SHOCK ABSORBER Filed Dec. 13, 1947 Patented ug. 22, 1950 SHOCK: 'ABSORBER `.Edwin-fl?.v iRossman, Dayton, Ohio, assigner to General Motors .Corporation, DetroieMich., a .corporation ofu Delaware Applicationfecemberv, 1947;Serial No. 791,565

(Cl. v`18S-.188)

I 12 Claims.

f lhisiinyentionxrelates to improvements. in hydnanlicishockiabsorbers,.:particularly .of the` direct acting time..

Aa hydraulic'fshock `absorber Yof the direct .actingfv typensit one'ihaving ...a cylinder `provided with. a closure membereat eachA end. Aipistoniin. theicylihderrrhas ifa:. r.o'd iattachedlthereto Which :slidably extends; throughi one cylinder closure pmemberf.

piston.'YH divides the cy1inder..into .twofiuidy displacementlfchamhers, one Aof vwhich has the pistenina-.oidnaxtending therethrough. lhe :piston hasetvahredzpassages .providing for: controlled.

transierzofcuidifrom onesi'de of vithelpiston .tothe otherrin response ;to its; reciprocation .the cylinde uid containing..r.eservoirfis...in .communicaf tionawith .thezcylinder *throughtza :two-.Way fluid.,

aw controlva'lv'e mechanism providedinthecylinder closure member opposite the onethrough which ztlieipistonvrod passes..

. :Ifii'lthis :typerof ".'shock '.absorber', as. ,the L. piston moves `ovizardzthe '.valved :closure member and: l pressureupon'theiiuid.betweensaid pis..

ton* andisaidlclosurefimember, .ay valve passage.` in

thefpstoriawill' be :opened to :permit f the-...displaced uiditoienteriintexthe cylinder-:chambericontaining thefpistonfrodz Due tothe presence of the rodbinffthis'Y chambergzall ffluid displaced from 2 the` opposite.;'cylinderchamberecannot :bei received :so

that itmiay bei said itha't [ther .piston rod` displaces thatiportionfofithe fluid,vordinari1y receivable if theirod .were not presentinvsaid chamber. There#- foresltiiis -rA rod displaced iiuid `effects vthe opening orthezprassure relief @valve .portionof the :mechanism inthe'fonellcylinder closure member toestablish-a uidfflw from the cylinderintoltheffluid reservoir. y

Upon reversed movenieritfof the piston itexerts pressureiup'on the fluid in :the .rod containingccylinder chamber, effecting opening ofifanother Vlved passage liniathe piston .and providingior thefiftransferifofxuid into the opposite cylinder cirzm'iber-` 'mheffamount of .iiuidimthesmaller capacity, .rodi containing u.chamber .is insufficient to meet Athe volumetric Vrequirementsor. the :cylinderchamberintoxwhich fluid is being transferred,4 thusi'th'e intakevaive .portionofthei meclri-v anismirrxthacyiinder closuremember isioperated tot .permita .ficwiroi 2i-luid. .from Ithe reservoir4 into the .cylinderifchamberrsuiicient to satisfy its yolumetricrequirements.`

Uhusain `fthe. fordinary.- 'directiactina `zlriydraulic' shocicaabsorber; fluid is y.transferred directly betwecn theicyli'nder anduidreservoir. f

.it daemonsitheiobiectszofithe .presentinverition f 2. to z provdelia- ,direct acting, `hydraulic shock absorber: with :an :intermediate riiuid reservoir, termedzaccumulatorl hereinafter, Whichiis interposed--betweenfthe working cylinder and thermain transferred from and into'said workingfeylinder directly'ias the piston is reciprocated.

` 'A":1iurther-,-object-of the :present invention is to provide an-:expansible and'contractibleaccumulator; ithe -4fluid .in which is constantly under pressure during-theoperation -of r the shock absorber.

xA stili further-.objectief thepresent inventionds to provideiariuidgpfump'fbetween the accumulator and theimainfiuid reservoir, Vsaid pump being 'rendered.:automatical1y eilective, 'in response-to expandinggand contracting' movements of the accumulator, :to deliverfluid underpressure from themain iil'iid-.zreservoirinto the accumulator .to corripensate for:` any loss `of iiuidresuting from l internalfleaks, Vthereby maintaining the v olumetric-ieciency, .of :the .accumulator and 1 conseqiientiyrzthe shock; absorber.

AfAnoti'Ier:object vof the. present invention is to.

provide means' nfor'ipreventin'g ioverlling of `the accumulator f duringfshock absorber operation.

.Eurtheriobjectsiand advantages of the presentv invention Willbeapparentifrom the foilowingdesoription,rererenceibeingihad:to the accompanyairayvings, wherein apreferred'embodimentl ofithe presenttinvention .is clearly shown.

inthezdrawings r iEig;liisfa1ongitudiri-al fsectionaliview of a direct acting Ihydrauiic' shock' 'absorber I equipped with theepresent' invention.. In this View the accumulater/.iis` `shown.:com1;11ete1y contracted.` and unloaded. i

FigaEtisfa'ragmentorthe vier/'shown in Fig. 1, however inthis'i-.viewithe accumulatoriis shownlin extremecex'pandediposition,L

Referring to(` the '=drawings', the numeral 2S designatestheeouteritubeuofiithe shock absorber vihichziorms theiiiid reservoir 2a. This tubular member T20. hassacup-shaped cover 2i.V secured at' one tend Fin any :suitable `marmer preferably gby welding. This I-eird coyersorlcap -hiasfspaced radiali ribs 22a used forsupporting.' means as wili be described hereinafter.. To Ithis'end .'covertcap 22 tferetis attaclied;A preferably by Welding, ua ring 2" :abyimeans .tof whichtthisl end of thefshock fab'- serber is attached .to oneiofithe' relatively movable` members lAzvhoseimovement the shock absorber intendedztoccontrol. :Ait the. opposite end fof .tube ZO'IteLe-are :provided interior threads i. for :threadedlyzreceivingth'e `endheadioncles-uremember 24; The outeriend'urfaceiof the head .241Lisirecessed udfreseriloirfand into land from Which'luid is` to receive the packing gland 25. A central opening in the head member 24 axially aligns with an opening in the packing gland 25 and a shaft 25 slidably extends through the opening in the head member 24 and packing gland 25. The end of the rod 26 extending beyond the packing gland 25 has a disc 2l and a ring 28 secured thereto, preferably by Welding, the ring 28 being similar to the ring 23 and providing means for attaching this end of the shock absorber to the other relatively movable member whose movement the shock absorber is intended to control. One end of a tube 25 fits over and about the disc 2l, being attached thereto f to move therewith, this tube 29 surrounding the tube 25 and provides a protective shield about the tube 20.

A reduced diameter portion V3|] on the head member '24 is telescopically received in one end of the cylinder 3|. Therod 26 extends into this cylinder 3| and has the piston 52 attached thereto which piston divides the cylinder into the upper working chamber 33 and the lower working chamber 34. Piston 32 has through passages 35 and 35, the passages 35 being normally closed by a spring loaded valve 3'1, while passages 36 are normally closed by spring valve 38. These Vvalved passages 35 and 35 provide for controlled transfer of fluid through the piston in either direction as the piston is reciprocated in the cylinder. As piston 32 is moved upwardly, fluid is transferred from chamber 33 through the piston passage 35 into the chamber 34 and as the piston is moved downwardly in the opposite direction, iluid will be transferred from the chamber 34 through the passages 35 past valve 3l into the working chamber 33 of the cylinder.

The reservoir 2| is in communication with the recess in the head 24, containing the `packing gland 25, through passages 4i! in the head member 24. Said passages provide for the return of any fluid or Vair to the reservoir which, during operation of the shock absorber, may leak past the sliding connection between the piston rod 26 and head member 24 into the space in therecesses in head 24 beneath the packing gland 25.

At the end of the cylinder 3| opposite the head member 24 there is provided a compound valve mechanism for controlling the transfer of fluid between the accumulator space 'l5 and the cylinder chamber 34. This valve mechanism includes a valve cage 45 having a central orifice 4S and surrounding openings 4l, the central orifree being normally closed by a spring loaded` valve 48 yieldably urged upon the valve cage on the side thereof facing the chamber 34, while openings 41 are normally closed by springvalve 49 urged against the side of the valve cage 45 outside the cylinder 3|. Thus, valve 48 may be operated in response to movement of the piston 32 toward the head member 24 to permit vfluid to flow from the accumulator space 15 into the cylinder chamber 34, while valve 49 is operated to open its passages 4l in response to movement of the piston 32 toward the valve cage 45 to establish a restricted fluid iiow from the cylinder chamber 34 into the accumulator.

As has been stated heretofore, the feature of the present invention is to provide a hydraulic shock absorber of the direct acting type with an expansible and contractible accumulator in communication with the working cylinder of the shock absorber and a pump between said accumulator and the main fluid reservoir continually operative in response to expansion and contraction movements of said accumultor to de-A liver fluid under pressure from the main reser-1 voir into said accumulator.

This accumulator and pump comprises a cylinder 5i) having one end secured to a ring 5| which surrounds and supports the valve cage of the compound valve mechanism. Thi-s ring has outwardly extending ngers 52, the outer peripheral edges of which lie adjacent to the inner wall of the tube 20 thereby substantially centralizing the two cylinders 3| and 50 in the tubular shell 20. The other end of the cylinder 50 has an end cover member 53 tted thereon which rests upon the radial ribs 22a. in the cover cap 2|. It will be seen that as the head member 24 is screwed into the cover 2D, it will exert a pressure upon the cylinder 3| which pressure in turn is exerted through the valve cage 45 and ring 5| upon the cylinder 5|) to clamp the end cover 53 thereof into rigid engagement with the radial ribs 22a in the cover 22.

The end cover 53 has a central aperture 54 and an annular row of other apertures 55 surrounding said central aperture. Onthe inside surface of the cover 53 there is provided an annular ridge 56 surrounding the central aperture 54, this ridge forming a valve seat upon which the intake valve 5l' of the pump is yieldably urged by the spring 58. Spring 58 is retained in a recess in the end edge of a tube '60 which rests upon the end cover 53'. This tubular member 5D forming the pump cylinder extends coaxially into the cylinder 5i) being of comparatively lesser diameter than said cylinder. The movable wall of the accumulator 15 is in the form of a'iioating piston Si, slidably supported within the cylinder 56,' this floating piston having a hollow core 62 secured in a central opening in the head of piston 5|, said core, forming the piston of the pump, being telescopically received by and slidable in the tubular member or pump cylinder 50. A valve seat S3 is provided within the hollow core E2 of the floating piston 6| and a valve 54 is yieldably urged upon said valve seat 63 by. spring 55. Both valves 5l and 64 operate in the same direction, that is, both may be lifted from their normally engaged seats to permit fluid to ow pastV said valves in one direction only. A coil spring 'l0 is interposed between the movable wall of the accumulator or as termed the floating piston 5| and an outwardly extending annular flange on the tubular member or pump cylinder 55, this spring maintaining said pump cylinder 50 upon the end cover 53 of cylinder 50 and yieldably urging the floating vpiston 5| toward the cylinder 3| normally maintaining said floating piston in engagement with the ring 5| as shown in Fig. l, in which position the accumulator is completely contracted.

A series of bleeder holes l2 are provided in the wall of the cylinder 50, these bleeder holes normally being closed by the floating piston 6|. However, when said piston 6|* is moved a predetermined distance from engagement with ring 5| or its normal position, bleeder holes 'I2 will be uncovered to provide communication between the reservoir 2| and the accumulator space l5A within the cylinder 50 between the floating piston 6| and the compound valve mechanism in the cylinder 3| thereby venting this space.

:l collapsed position. If due to separating move- In the Fig. 2, the piston 6| is shown in the position' in which the bleeder holes 12 are venting the '7 tion; a two-Way fluid ow control mechanism in the cylinder; an expansible and contractible accumulator with which said control mechanism communicates; means yieldably acting upon the accumulator to contract it; means comprising one element of the accumulator, said means being opt erative in response to accumulator action, for

municates; means yieldably acting vupon the accumulator to contract it; means, one portion of which comprises one member of the accumulator, said means being operative in response to contraction of the accumulator, to draw a supply of fluid from the fluid reservoir and in response to expansion of the accumulator to deliver fluid in said means to the accumulator; and means directly connecting the accumulator with the reservoirlin response to predetermined expansion of the accumulator.

6. A hydraulic shock absorber comprising in combination, a cylinder; a fluid reservoir; a positively actuated. piston in the cylinder, said piston having valved passages providing for the transfer of fluid through the piston in either direction; a two-way fluid flow control mechanism in the cylinder; an accumulator comprising a cylinder, one end of which is in communication with the two-way control mechanism, said cylinder containing a partition member longitudinally reciprocative therein and normally yieldably urged toward and against the said one end thereof; a pump between the accumulator and fluid reservoir, said pump comprising a, cylinder having a valved Vclosure member at its one end and a valved piston formed by an extension on the movable partition member of the accumulator and slidably fitting into the pump cylinder, the valves in said pump cylinder and piston acting in the same direction, one to permit fluid to enter the pump cylinder as the accumulator partition moves to inject luidinto the cylinder, the other to inject fluid from the pump cylinder into the accumulator as the accumulator partition is moved by fluid pressure from the fluid flow control mechanism in the shock absorber cylinder; and means rendered effective upon predetermined movement of the accumulator partition, directly to connect said accumulator with the reservoir independently of the pump.

7. A hydraulicV shock absorber comprising in combination, a cylinder; a fluid reservoir; a positively actuated piston in the cylinder, said piston having valved passages providing for the transfer of fluid through the piston in either direction;

a two-Way iluid flow control mechanism in theV cylinder; an expansible and contractible accumulator chamber and a fluid pump interposed between the shock absorber cylinder and the fluid reservoir, the piston of the pumpforming the movable Wall of the accumulator chamber, said Wall being yieldably urged by a spring toward the shock absorber cylinder, the cylinder of the pump in Vwhich the movable wall reciprocates, being rigid: statignaiy by seid spring. both puma pis:l

ton and cylinder having normally closed-valves. the cylinder valve providing for a flow of iluid from the reservoir into the pump cylinder when the movable wall of the accumulator is spring actuated, the, piston valve beingoperative to effect fluid from the pump cylinder to be forced into the accumulator when the movable wall thereof is actuated against the effect of the spring; and vents rendered effective by predetermined expansionof the accumulator chamber, directly to connect Vsaid chamber with thereservoir.

8. A hydraulic shockabsorber comprising in combination, a cylinder; a` fluidY reservoir; a positively actuated piston in the cylinder, said piston having valved passages providing for the transfer of fluid through the piston in either direction; a two-Way fluid flow control vmechanism in the cylinder; an expansible and contractible accumulator in communication with `the shock absorber cylinder, said accumulator having a movable Wall normally yieldably urged to contract the accumulator; a pump cylinder having a normally closed, intake valve in its end in communication with the reservoir; an extension onA the movable wall of the accumulator, slidably fitting into the pump cylinder and forming the piston therefor, said extension having a, normally closed valve operative to provide for the transfer of fluid from the pump cylinder into the accumulator when the movable wall of said accumulator is actuated by fluid displaced from the shock absorber cylinder; and accumulator venting ports rendered effective directly to connect the accumulator with the reservoir in response to predetermined expansion of said accumulator.

9. A hydraulic shock absorber comprising in combination, a cylinder; a fluid reservoir; a positively actuated piston in the cylinder, said piston f having valved passages providing for the transfer of fluid through the piston'in either direction; a two-way fluid flow control mechanism in the cylinder; an expansible and contractible accumulator comprising a cylinder in communication with the shock absorber cylinder by having one end secured thereto, the other end being provided with a perforate end member having a central opening and other'surrounding openings; a movable partition in the accumulator cylinder; a spring yieldably urging said partition toward the shock absorber cylinder; a fluid replenishing pump 'interposed between the accu-y mulator and the uid reservoir, said ypump comprising a cylinder within the accumulator cylinder and urged upon the end member thereof by the aforementioned spring; a spring loaded Valve in the pump cylinder normally closing the central opening in the end member; a piston in said pump cylinder, attached to the movable partition and having a normally closed valve operative to permit fluid fromthe pump cylinder to be forced into the accumulator in response to actuation of the partition by fluid displaced from'the shock absorber cylinder; and means, rendered effective in response to predetermined expansion of the accumulatonfor directly connecting said accumulator with the reservoir. v

10. A shocl: absorber in accordance with claim4 9 in which,V however, the accumulator cylinder has ports normally covered by the movable end Wall ,therein but adapted to be uncovered and. directly, connect the interior of vthe accumulator With the reservoir when the said movable wall isy actuated into a predetermined positionbylfluid displaced from the shookabsqrberlcylinder,

l1. A hydraulic shock absorber comprising in combination, a cylinder; a fluid reservoir; a positively actuated piston in the cylinder, said piston having valved passages providing for the transfer of fluid through the piston in either direction; a two-Way iluid flow control mechanism in the cylinder; an expansible and contractible accumulator in communication with the shock absorber cylinder; a spring constantly exerting a force upon the accumulator to contract it; a pump, the cylinder of which has a normally closed intake valve in communication with the iiuid reservoir, the piston of the pump being connected to and actuated by a movable portion of the accumulator, said piston having a, normally closed valve operative `in response to eX- pansion of the accumulator, to permit fluid from the pump cylinder to .be injected into the accumulator; and means rendered eiective by predetermined expansion of the accumulator for connecting said accumulator with the reservoir independently of the pump.

12. A hydraulic shock absorber comprising in combination, a cylinder; a fluid reservoir; a positively actuated piston in the cylinder, said piston having valved passages providing for the trans- 25 fer of fluid through the piston in either direction; a two-way uid flow control mechanism in the cylinder; an expansible and contractible accumulator in communication with the shock absorber cylinder and expansible by the fluid displaced from said cylinder; a pump having a cylinder provided with a normally closed intake valve in communication with the fluid reservoir; a spring interposed between the pump cylinder and the accumulator, said spring holding the pump cylinder in position and urging the accumulator into `contracted position, said pump cylinder having a valve piston secured to and operative by the accumulator to draw fluid into the pump cylinder when the accumulator is being contracted and to force the fluid from the pump cylinder into the accumulator when said accumulator is expanded; and means operative directly to connect the accumulator with the reservoir in response to predetermined expansion of said accumulator.

EDWIN F. ROSSMAN.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED ySTATES PATENTS 

